1. Field of the Invention
The invention relates to the field of chemical batteries, and more particularly to a positive electrode material for a lithium-ion battery and a preparation method thereof.
2. Description of the Related Art
As a new generation of high-energy battery, the lithium-ion battery features light weight, high power density, high working voltage, and pollution free. Positive electrode materials are critical for manufacturing of the lithium-ion secondary battery, and are the primary factor to determine the performance and the value of the lithium-ion battery.
Studies of the positive electrode material for the lithium-ion battery are mainly focused on lithium-transition metal composite oxides, which include: LiCoO2, LiNiO2, LiMn2O4, and other ternary materials. These positive electrode materials have different disadvantages. For example, LiCoO2 is expensive and has low safety performance. LiNiO2 has a low working voltage and complex synthesis.
LiMn2O4 is characterized in its good stability, pollution free, high working voltage, low price, and convenient synthesis, and thus is widely used for preparation of a positive electrode material for a lithium-ion battery. However, as a positive electrode material, LiMn2O4 has the following defects: 1. Upon LiMn2O4 discharging, Jahn-Teller effect occurs, thereby destroying the spinel structure of LiMn2O4 and affecting the capacity and cycle performance thereof; 2. LiMn2O4 is solvent-sensitive in an electrolyte; and 3. the electrolyte is prone to decompose whereby producing a passive film on the surface of the electrode and resulting in self-discharge phenomenon. As a result, conventional positive electrode materials made of LiMn2O4 have an obvious capacity loss in use.